The biggest complaint that patent attorneys hear from clients regarding the patent process is the long time it takes to get a patent.  Well… the flip side to this is that occassionally it is the applicant which causes most of the delay.  And under the doctrine of prosecution laches a defendant can assert that a patent is unenforceable if the delay is deemed unreasonable.  However, there’s more to it than that.

In the case of Cancer Research Technology Ltd. v. Barr Laboratories, Inc., decided last week, the patent applicant filed 11 continuation applications and abandoned 10 applications, taking over a decade to finally obtain the patent on a new drug.  Later, when Cancer Research Technology sued Barr Labs for patent infringement, the defense of laches was raised, and the case was dismissed on the ground that the applicant unreasonably delayed the prosecution of the patent.

On appeal, however, the Federal Circuit made clear that laches requires also a finding of prejudice.  This would usually mean that the accused infringer invested in the technology or used the claimed technology while the plaintiff was still prosecuting the patent application.  Since Barr did not show this to be the case, the Federal Circuit reversed the decision of the lower court.  (The Court also reversed on the lower court’s finding of inequitable conduct).

An interesting case… and one to note when prosecuting a patent or later asserting patent rights.